Small palladium islands embedded in palladium–tungsten bimetallic nanoparticles form catalytic hotspots for oxygen reduction

Our most recent article has been published in the journal of Nature Communications, and here, we report a unique novel Pd-W alloy with a Pd content of only 11 At%, which has a similar efficiency as a pure platinum catalyst. This excellent efficiency is explained by the unique morphology of the Pd-W nanoparticles. By advanced experimental and theoretical investigations, we show that the alloy is composed of metallic Pd-islands embedded in a W matrix. The size of the islands are about 1 nm in diameter and are composed of 10-20 atoms that are segregated to the surface. The unique formation of the material is based on the synthesis method, which is performed in an ordinary kitchen micro-wave oven. This study has been conducted in “The artificial leaf” project which is funded by Knut and Alice Wallenberg foundation to physicist, chemists, and plant science researchers at Umeå University.

Guangzhi Hu, Florian Nitze, Eduardo Gracia-Espino, Jingyuan Ma, Hamid Reza Barzegar, Tiva Sharifi, Xueen Jia, Andrey Shchukarev, Lu Lu, Chuansheng Ma, Guang Yang, and Thomas Wågberg

Nature Communications 5, Article number:5253 (2014)

Abstract

The sluggish kinetics of the oxygen reduction reaction at the cathode side of proton exchange membrane fuel cells is one major technical challenge for realizing sustainable solutions for the transportation sector. Finding efficient yet cheap electrocatalysts to speed up this reaction therefore motivates researchers all over the world.

Here we demonstrate an efficient synthesis of palladium–tungsten bimetallic nanoparticles supported on ordered mesoporous carbon. Despite a very low percentage of noble metal (palladium:tungsten=1:8), the hybrid catalyst material exhibits a performance equal to commercial 60% platinum/Vulcan for the oxygen reduction process. The high catalytic efficiency is explained by the formation of small palladium islands embedded at the surface of the palladium–tungsten bimetallic nanoparticles, generating catalytic hotspots. The palladium islands are ~1 nm in diameter, and contain 10–20 palladium atoms that are segregated at the surface. Our results may provide insight into the formation, stabilization and performance of bimetallic nanoparticles for catalytic reactions.

Nature Communications 5, 5253 (2014)